Influenza (Flu)

Novel and Variant Influenza A Viruses

Flu viruses constantly change and mutate. Novel and variant influenza A viruses can infect and cause severe respiratory illness in humans. These influenza viruses are different from currently circulating human influenza A virus subtypes and include influenza viruses from predominantly avian and swine origin.

In recent years, human infections with highly pathogenic influenza A (H1N1, H5N1, H5N2, H7N3, and now H7N9), and variant influenza A (H3N2v and H1N2v) viruses have been reported.